Sofa



FIG. 1 is a perspective view of a sofa, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a rear view thereof. 

The ornamental design for a sofa, as shown. 